The "slap tongue" effect dates back to at least a 1928 in a piece of published music. Some contemporary classical music arrangements have made use of the effect but I do not remember that name of the compositions. I recall hearing the sax section in a 40s big band movie using it in a novelty type arrangement. James Brown's tenor player, J. C. Davis used it on the 1962 version of "Night Train" in the 2nd part of the melody as an 8th note answer to the low C that is played at the end of the melody line.
Another point of view from a contributor on a sax message board indicates "the technique actually originated in jazz & pop. First record I can recall offhand is a 1923 King Oliver side with an obscurity named Stump Evans playing the C melody. By '24 Rudy Wiedoeft and Coleman Hawkins had picked it up. Bennie Krueger was another novelty sax guy, and I think he did it too. You might have thought it came later to pop/jazz, because it got corny very quickly and disappeared from popular taste."

Jazz artists John Klemmer, James Carter and Yoseff Lateef have all used it in their solos.

The sound is created as a result of the release of suction in the mouth and the popping sound that the reed produces which amplifies as it travels through the horn.

Lay the tongue against a lot of the reed. Gently push upward so that the tip and rail of the reed is closed. Get rid of as much air in the oral cavity as you can and seal off the lip so that you have an airtight fit. The tongue is quickly released in a downward motion. When you release the tongue downward, you also drop your jaw and open your mouth in a "popping" motion. This is all done very quick. DO NOT pull the tongue back towards your throat. It needs to pop downward away from the roof of the mouth to get the most volume. Do not blow air through the horn and do not inhale when you release the tongue.

Low F or G fingering works the best for me. They produce the most volume but I would imagine that fingerings differ from player to player. Hope this helps.

Additional info from a sax message board; While I was learning how to slap tongue, I came across this. I forget where I got it, perhaps the NASA listserv, but, who knows. I've listed the author at the bottom so as NOT to take credit for the information that follows. Hope this helps;

Slap-tonguing requires some time and patience to develop. Most people take several months of attempts before they get a true slap on the attack. Things to keep in mind are:

1. Make certain you use your normal embouchure for the pitched slap tongue. The non-pitched variety requires that you pull the lower jaw away from the mouthpiece in one motion as you articulate; but the pitched variety requires that you keep your normal embouchure through the process.

2. It is far easier to slap tongue on low notes than high. Think about the heavy clicks we tend to get in the low register with the tongue when we're not careful. These are mild slap tongue sounds, so try it on your low Bb and B until you have some success. Also, you might want to begin on the tenor or baritone saxophone until you have the feel for it.

3. Place your tongue on the entire exposed reed inside your mouth. Cover the whole reed with the tongue and do some short, staccato articulations. This generally leads to a heaviness, or a "click" at the beginning of the articulation, much like what a beginning student would get. Eventually this tends to work better when you do not end the tone with the tongue, and again, this sound is especially easy to produce in the low register.

4. The amount of tone you want to have with the slap tongue is determined by the amount of air you put through the instrument -- it is not determined by the tongue. You can play either a very short note, or a very long note or passage of notes with the slap as a beginning attack. I find that the shorter notes seem to be easier to produce the slap, at least initially.

5. Basically, the slapping procedure involves pulling the reed away from the mouthpiece with the tongue. When the strength of the reed is too much for the tongue, it pulls away and cracks back against the mouthpiece, producing the slap sound. Over time I have learned to do this with far less effort than I thought was necessary originally. Most people who concentrate on the tongue flicking the tip of the reed initially tend to break a lot of reeds, so you may want to do this on a softer, old reed that won't be on your recital program any time soon.

Cliff Leaman Associate Professor of Saxophone University of South Carolina Columbia, SC 29208